MULTIPLE_SUBGRAPHS

This error occurs when you call a subgraph inside a node multiple times, and the subgraph is compiled with checkpointer=True (continuations mode).

Troubleshooting

Choose one of the following based on your requirements:

Don’t need interrupts? Use checkpointer=False to opt out of checkpointing entirely:
```
subgraph = subgraph_builder.compile(checkpointer=False)
```
Need interrupts but not cross-invocation persistence? Use the default inherited mode by omitting checkpointer:
```
subgraph = subgraph_builder.compile()
```
Each invocation gets a unique namespace, so parallel execution works. The subgraph starts fresh each time but can use interrupt().
Need cross-invocation persistence? Use checkpointer=True. LangGraph assigns each invocation a position-based namespace suffix (calling_node, calling_node|1, etc.) to prevent conflicts. For stable, name-based namespaces, wrap each subgraph with a unique node name — see parallel subgraphs.

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